NORMAL HISTOLOGY. 



FIG. 84. 



P 1 



The axis-cylinder processes usually are directed towards the 

 nearest mass of white matter, since the axis-cylinder of the nerve- 

 fibre becomes continuous with that of the cell. Exceptional 

 arrangements are sometimes encountered, as where one process 



of a bipolar cell becomes wound about 

 the remaining straighter fibre, con- 

 stituting a spiral process ; such cells 

 are comparatively frequent in the sym- 

 pathetic ganglia of the frog. 



Ganglion-cells lie within peri-cellu- 

 lar lymph-spaces, which appear with 

 greater or less 

 FIG. 85. distinctness ac- 



cording to the 

 condition of the 



FIG. 



Nerve-cell of first type from cere- 

 bral cortex : ft, /, protoplasmic pro- 

 cesses directed respectively towards the 

 free surface and laterally ; a, axis-cylin- 

 der or nerve- process giving off collateral 

 branches, c, c. Golgi staining. 



Nerve-cell of second type 

 from cerebellum : p, branched 

 protoplasmic processes ; c, cell- 

 body ; a, axis-cylinder process 

 breaking up into rich plexus 

 (), but entirely confined to 

 gray matter. Golgi staining. 



Basket - work, formed 

 by the extensions of the 

 branched ax is -cylinder 

 process of a nerve-cell, 

 surrounding the body of 

 one of the ganglion-cells 

 of Purkinje : /, base of 

 branched process of Pur- 

 kinje'scell ; n. fibrils con- 

 stituting basket-work. 



protoplasm of the enclosed cell ; when this is contracted and 

 shrunken the space is, obviously, more conspicuous than when almost 

 entirely filled by the cell. These lymph-spaces are limited by 

 a delicate, elastic, hyaline membrane, and lined with nucleated 

 endothelial plates ; on the exit of the axis-cylinder a delicate 

 prolongation of this sheath accompanies the fibre as the neuri- 

 lemma. 



NERVE-FIBRES. 



Depending upon the character of the investing coats, nerve-fibres 

 appear as two kinds the medullated, or white, and the non- 

 medullated, or gray. These do not, however, constitute two 

 sharply defined and distinct classes, but depend upon variations in 

 the condition of fibres, which often represent both varieties at dif- 



